Tudor Hill Observatory

In a project commissioned by the National Oceanic and Atmospheric Administration’s (NOAA) Earth Systems Research Laboratory (ESRL) the Bermuda Institute of Ocean Sciences (BIOS) has been the cooperating agency responsible for measuring the concentration of key atmospheric atmospheric gas species at Tudor Hill in Bermuda. This is part of NOAA/ESRL’s Global Monitoring Division’s aim to track changes in these key gas species, particularly focusing on their sources, sinks, global trends, and distributions.

One of the more well known gases measured at these types of observatories, including Tudor Hill, is Carbon Dioxide. An infamous greenhouse gas emitted largely through the burning of organic matter (ie. fossil fuels), the increase in Carbon Dioxide can be seen even in the middle of the Atlantic at Tudor Hill, Bermuda.

Another interesting feature is the seasonal change in Carbon Dioxide concentration controlled mainly by the biosphere. Because there is more land in the northern hemisphere, the biosphere’s influence is disproportionally weighted to what is happening in the northern hemisphere. During northern hemisphere summer, there are more photosynthetically active plants taking in more Carbon Dioxide globally than during northern hemisphere winter.

Measurements of concentration of Carbon Dioxide gas at Tudor Hill Bermuda since records began in 1989, including preliminary 2016 data in orange. Plotted with NOAA/ESRL’s interactive data viewer.

Attributing the trend in Carbon Dioxide to human activity is a little more complicated than just observing the trend. It comes through analysis of Carbon isotopes bonded in Carbon Dioxide. Carbon comes in two naturally occurring stable isotopes: Carbon-13 (13C) and Carbon-12 (12C). 13C has an additional neutron and therefore has slightly more mass and slightly different chemical properties.

It has been found that the biosphere (ie. plants) preferentially uptake the lighter 12C containing molecules during photosynthesis. This leaves behind less 12C in the atmosphere and so the ratio 13C/12C increases. The higher proportion of 12C in organisms is maintained even if they should become fossil fuels. When we burn organic matter (ie. fossil fuels) we release Carbon Dioxide with higher proportions of 12C into the atmosphere and the ratio 13C/12C measured in the air decreases as a result.

One way to measure the relative amount of the two stable Carbon isotopes is called “delta 13 Carbon” (δ13C). Here, the measured ratio 13C/12C is standardized by a reference ratio determined from reference research into the average properties of Carbon. That standardization is very close to one, and all the variations occur in the thousandths decimal. In practice, one is subtracted from it and then the result is multiplied by 1000.

A trend of decreasing δ13C is observed at Tudor Hill, Bermuda. This trend lends support to the idea that not only are atmospheric Carbon Dioxide concentrations increasing, but the increase might be due to human activity.

All available delta thirteen C data for Tudor Hill, Bermuda. Records of this parameter are kept since 1991, including preliminary 2016 data points. Plotted with NOAA/ESRL’s interactive data viewer.

These trends and patterns are repeated across the world. It is clear that the upswing in Carbon Dioxide is not a local phenomenon, but a symptom of a global problem.

Many more projects, providing invaluable scientific insight rely on data like this collected at Tudor Hill in Bermuda and around the world. Bermuda has proved to offer a unique location to get continuous long time-series of the largely undisturbed samples of the low-level ambient marine atmosphere. As such, I expect research to continue or expand in Bermuda, particularly as issues such as increasing Carbon Dioxide concentrations become more pressing.